Photo: Reproduction.
The cause of the mysterious mass death of African elephants may finally be clarified: Scientists have pointed out in a report that bacterial outbreaks are the most likely cause of the mammals’ deaths.
Between the end of August and November 2020, 35 African elephants died under previously unknown circumstances in the northwest of the African country Zimbabwe. Eleven of the herd’s giant animals died within 24 hours. Poaching, poisoning and drought were the prevailing hypotheses until then.
However, a bacterial infection killed the elephants, the study found using samples from 15 dead animals in Zimbabwe.
“They died in a very narrow window. “That was one of the most puzzling parts of the whole puzzle,” said Dr. Chris Foggin, a veterinarian with the Victoria Falls Wildlife Trust in Zimbabwe, who coauthored the study into the animals’ cause of death.
“We know that there is a possibility that many animals could die very close to each other, but not next to each other, in such a short period of time. In my opinion it is really unique, especially in this part of the world,” added Dr. Chris Foggin added.
Also at the beginning of 2020, around 350 elephants suddenly died within three months in northern Botswana another country in Africa. Authorities and experts were initially unable to explain the deaths which occurred in the continent’s largest elephant population.
An analysis published October 25 in the journal Nature Communications found evidence of an infection by a littleknown bacterium called Bisgaard taxon 45, which caused the infections, or blood poisoning, in the mammals.
Elephant mortality in Botswana is attributed to cyanobacterial neurotoxins, but further details have not been published, the study says. Foggin said there was no proven link between elephant deaths in Zimbabwe and Botswana.
The deaths came amid dwindling food and water resources during the dry season, forcing elephants to travel ever greater distances in search of water and food.
The study authors said heat, drought and population density in the area likely contributed to the bacterium outbreak. The trend, scientists say, is that extreme conditions drought and food shortages are becoming more common as the Earth warms, which could lead to more elephant deaths in the future.
“It is premature to say that climate change has directly affected animal deaths, but it could do so in the future if there are longer droughts or rainfall patterns change and we have a much more severe dry season,” Foggin said. “I think if that’s the case, it’s more likely that this type of mortality event will happen again.”
An endangered species
The African elephant is an iconic species that is under significant pressure from poaching and habitat loss. According to the study, the population, classified as endangered on the International Union for Conservation of Nature’s Red List, declined by 144,000 to about 350,000 between 2007 and 2014, with ongoing losses estimated at 8% each year.
Around 228,000 elephants live in the KavangoZambezi Transfrontier Conservation Area 500,000 square kilometers of protected land, around 90% in Botswana and Zimbabwe.
Evidence of infection was found in six of the 15 samples, the study authors wrote, which was confirmed by laboratory isolation of the bacteria and indepth genetic analysis.
There was no evidence of toxins, including cyanobacteria, or viral infection.
Harmful delays
Additionally, no dead scavengers or other wildlife were reported or observed near dead elephants, as would be expected with cyanide or other intentional poisonings, the study said.
“Although there was no cultural or molecular evidence confirming Bisgaard taxon 45 in more than six deaths in Zimbabwe, the elephants examined were in good physical condition and are unlikely to have died solely from droughtinduced starvation or severe dehydration are,” he noted. the study.
No elephants had their tusks removed due to poaching and no external signs of trauma were observed. Tests for anthrax also came back negative, Foggin added.
The researchers said they were unable to detect the bacteria in the other samples a fact they attributed to poor sample quality and delays in obtaining the necessary permits, meaning it was too late to carry out laboratory work.
“The majority of the carcasses were degraded at the time of sampling, making the quality of the first sample poor. “In addition, exporting wildlife samples for analysis requires obtaining multiple licenses from different entities a process that can take months,” the study said.
What is known about the bacteria?
Bisgaard taxon 45 has been linked to tiger and lion bite wounds to humans. The bacterium was also found in a squirrel and healthy parrots in captivity.
The microorganism, which has no official name, is closely related to another, more common bacterium called Pasteurella multocida, which can cause hemorrhagic septicemia in other animals, including Asian elephants.
This bacterium has also been linked to the mass dieoff of 200,000 critically endangered saiga antelopes in Kazakhstan in 2015, the study said.
Foggin said researchers have been monitoring wildlife in the area for the presence of the bacteria, but no additional elephant deaths as a result of Bisgaard taxon 45 have been confirmed since 2020.
Photo credit: CNN.